Ratko Mladic, shown in 1993 and after his arrest in 2011, is charged with Bosnian war atrocities. Photograph: Reuters

Ratko Mladic goes on trial in The Hague on Wednesday charged with masterminding atrocities in Bosnia during the 1992-95 war.

Twenty years after Serbian forces unleashed their campaign, Mladic will enter the international criminal court's Yugoslav war crimes tribunal as a frail 70-year-old, a far cry from the swaggering general who commanded Serb forces during a war that left 100,000 dead.

"I don't have to tell you how important it is that finally this trial can start, 17 years after the first indictment was issued [against Mladic]," said the court's chief prosecutor, Serge Brammertz.

Mladic has waived the right to make a statement on Wednesday and Thursday as prosecutors lay out an overview of their case. The first witness is due to testify on 29 May.

The tribunal's president, Theodor Meron, has rejected a last-ditch effort by Mladic to have the Dutch presiding judge replaced because of alleged bias, and to delay the trial.

For years after the war, Mladic was one of the world's most-wanted fugitives. His time on the run finally ended in 2011, when Serbian forces arrested him near Belgrade and flew him to The Hague. He has been waiting for his trial in the same jail as his former political leader, Radovan Karadzic, who was arrested in 2008 and is now at the midway point of his own trial, on almost identical charges to Mladic's.

"We would of course have preferred having both before the same judges, one being the political architect of the crimes allegedly committed, the other the military leader of this policy," Brammertz said.

Both men are accused of leading Bosnian Serb forces responsible for atrocities that started with a brutal campaign of ethnic cleansing in 1992 and reached their peak in July 1995 with Europe's worst massacre since the second world war, the slaughter of 8,000 Muslim men and boys in the northern enclave of Srebrenica. They are also charged in the deadly campaign of sniping and shelling during the 44-month siege of the capital, Sarajevo.

Brammertz said prosecutors would present testimony from more than 400 witnesses, most of it as written statements presented to judges. Prosecutors have a total of 200 hours to present their case before Mladic begins his defence. If he is convicted, Mladic faces a maximum sentence of life imprisonment.

The man seen as the overall architect of the Balkan wars of the 1990s, the former Yugoslav president Slobodan Milosevic, died of a heart attack in his cell in 2006 before tribunal judges could deliver verdicts in his trial.

Mladic suffered at least one stroke while in hiding after his indictment and has been in ill health in The Hague.

"Victims are afraid that Mladic could die, and that would be very disappointing for the victims in Bosnia. I want a verdict for Mladic so that the whole world will see that he is a war criminal and has committed the crimes in Bosnia," said Kadefa Mujic, 42, from Srebrenica, a representative of the group Mothers of Srebrenica who met on Tuesday with Brammertz in The Hague.

Munira Subasic was in Srebrenica in 1995 seeking sanctuary with thousands of other residents in a UN peacekeepers' compound. She said she still remembered Mladic threatening the base's Dutch commander and ordering men to be separated from women. "Surrender your weapons and I will guarantee you life," he told the Bosnian Muslim men and boys, some as young as 11. "You can survive or you can disappear."

But it was those who obeyed who disappeared. Their bodies are still being found in mass graves scattered around the town. Thousands who refused managed to flee through the hills to freedom.

Mladic has refused to enter pleas to any of the 11 charges against him but he denies wrongdoing. He argues that his army was defending the Serbs in Bosnia.